<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        // let str = 'abc';
        // let str1 = "abc";
        // let str2 = `abc`;
        // let str3 = '';  // 空字符串
        // console.log(typeof 11); // number
        // console.log(typeof '11'); // string

        // console.log(1 + 1); // 2
        // console.log('1' + '1'); // 11

        let age = 18;
        document.write('我今年' + age + '岁');

        
    </script>
</body>
</html>